JP2013535731A - Energy saving circuit, trunk configuration and energy saving method for mains powered equipment - Google Patents

Abstract

The present invention includes a trunk circuit having a converter circuit (5) for generating an operating voltage (V _OUT ) for a device (PD) from a supply voltage (V _PSE ) that can be provided via the trunk system. The invention relates to an energy saving circuit (6) for a powered device (PD). The energy saving circuit (6) comprises at least one switching element (8) for disconnecting at least one electrical connection between the main system and the converter circuit (5), and switch on and / or switch Supplying at least one control circuit (9) for operating at least one switching element (8) in dependence on a control signal received by the device for turning off and operating energy to the control circuit (9) And at least one energy buffer for storing energy of voltage pulses (10, 11) provided via the trunk system. The present application further relates to trunk configuration and energy saving methods.

Description

ENERGY SAVING CIRCUIT FOR NETWORKED POWERED DEVICE, NETWORK CONFIGURATION AND METHOD The invention relates to an energy saving circuit having a converter circuit for generating an operating voltage for the device. Furthermore, the present application relates to a network configuration having a supply unit and at least one network powered device, and to an energy saving method for the network powered device.

  The prior art discloses various methods and apparatus for powering electrical devices remotely and over a network. As an example, the IEEE standard 802.3af, known as “Power over Ethernet” (PoE), is used over a network line in a local area data network (LAN). Thus, an implementation of supplying a supply voltage to a network component having a relatively low power draw between about 5 W and 15 W is disclosed.

  The advantage of the network power supply of the device is first that a separate power cable or power unit can be eliminated in the vicinity of the device. Furthermore, the supply of power to the associated devices can be centrally protected for all network powered devices by an uninterruptible power supply to the supply unit.

  FIG. 1 shows a configuration of the problem type for remote feeding of a network powered load (powered device, PD). The network-powered device PD is connected to a supply unit (Power Sourcing Equipment, PSE) by a network cable 1.

  In the configuration shown, the network cable 1 has two pairs of wires. A pair for simultaneous transmission (TX) and reception (RX) receive. The transmission signal and the reception signal are each transmitted as a high frequency AC voltage signal. These high-frequency AC voltage signals are applied on the DC voltage by two transformers for the supply unit PSE. The applied DC voltage is used as the supply voltage for the network-fed device PD, in which it is isolated from the high frequency AC voltage by two further transformers.

  The supply unit PSE has a voltage source 2 for supplying a supply voltage. Furthermore, the supply unit PSE has a monitoring circuit 3 that selectively connects the voltage source 2 to the transformer of the supply unit PSE. The network-powered device PD has a rectifier 4 and also has a converter circuit 5 that converts the supplied supply voltage into an operating voltage for the network-powered device PD.

  In order to avoid unnecessary power and transmission losses, the supply unit PSE has means for recognizing whether a network-powered device PD is connected to the network cable 1. In addition to recognizing whether the network-powered device PD is actually connected to the supply unit PSE, the means is for recognizing one of the various power classes for the network-powered device PD. Is also used. To this end, the monitoring circuit 3 monitors the voltage drop of the supply voltage across the resistor R and thus determines the internal resistance of the indirectly connected device PD. If the current through the resistor R falls below a predetermined threshold, the monitoring circuit 3 of the supply unit PSE assumes that the network-powered device PD has been disconnected from the network cable 1 and switches the switching element Sw, eg a relay or The supply of supply voltage is interrupted by the semiconductor switching element.

  The above-described configuration and related protocols for device recognition are suitable for drawing network components that typically draw approximately constant operating current and remain switched on during network operation. However, there is a problem when supplying power to a terminal that is switched on and off under user control.

  If such a terminal has an excessively low power consumption in the switched off or energy saving state below a predetermined limit value, the supply voltage from the supply device PSE is completely interrupted, as a result The terminal can no longer be awakened from the switched off or energy saving state by the device PD. On the other hand, if the network-powered device's internal resistance is too low and the supply unit also recognizes a network-powered device that is switched off or in an energy-saving state, the supply unit is continuously initialized. Run the sequence. This results in a poor energy balance for both the network-powered device and the supply unit, thus possibly violating the operating conditions of such a device.

  Accordingly, it is an object of the present invention to describe an energy saving circuit for a network powered device that completely or partially solves the above-mentioned problems. Furthermore, the aim is to describe a network configuration suitable for supplying power to devices that are network powered in a manner sufficient in terms of energy. Finally, the aim is to define an energy saving method for network powered devices.

  The object mentioned above is an energy saving circuit for a network powered device, comprising a converter circuit for generating an operating voltage for said device from a supply voltage that can be provided over the network. It relates to an energy saving circuit. The energy saving circuit includes at least one switching element that interrupts at least one electrical connection between the network and the converter circuit, and for switching on and / or switching off received from the device. At least one control circuit for actuating the at least one switching element based on a control signal, and for storing energy from voltage pulses provided via the network to supply operating power to the control circuit. At least one energy buffer.

  In order to provide a control circuit that can be operated almost independently of the converter circuit, and to supply operating power to the control circuit, voltage pulses provided via the network are supplied to an energy buffer. Buffering means that network power can be eliminated for network powered devices that are switched off or in an energy saving state. In this way, the power drawn by a network powered device that is switched off or in an energy saving state can be nearly zero without having to eliminate the advantages of network power and device activation and deactivation. Can be lowered. The supply unit used to supply power to the network-powered device can no longer recognize the device due to the high internal resistance when the switching element is open. This means that no initialization sequence is performed.

  According to one preferred refinement, the energy buffer is in the form of a capacitor. Here, the buffer capacitance is sufficient to supply operating power to the control circuit for a predetermined period of time. Providing a capacitor as an energy buffer is particularly inexpensive and at the same time allows the use of dangerous materials such as those found in rechargeable batteries in network powered devices. In this case, the capacitance of the capacitor can be set with respect to the period between voltage pulses, usually provided via a network that is predetermined by the standard.

  According to a further advantageous refinement, said at least one switching element is in the form of a semiconductor switching element that operates zero current, in particular a MOSFET. The use of a MOSFET or similar switching element allows the switched element's switched on and / or switched off state to be maintained by the control circuit without requiring operating current.

  The object described above is likewise a supply unit for recognizing a network-powered device and supplying a supply voltage thereto, and at least one network-powered device having an energy saving circuit based on one of the above-mentioned refinements. And at least one network cable interconnecting the supply unit and the at least one network powered device.

  Such a configuration complies with known standards for network powering of devices. Only devices that are powered by the network need be provided with an energy saving circuit as described above. On the other hand, no changes to supply units or network cables are necessary.

The above mentioned objects are also achieved by an energy saving method for a network powered device that includes the following steps:
Power from voltage pulses provided via the network is stored in the energy buffer,
The control circuit is operated with the power stored in the energy buffer,
A first device-side control signal for switching on a network-fed device is recognized by the control circuit;
A switching element is activated by a control circuit to make an electrical connection between the network and the converter circuit of the network-powered device.

  The method steps described above continuously monitor a network powered device for a control signal to switch on even when the converter circuit of the electrical device is electrically isolated from the network. Allow to do. This means that the energy device can be reactivated even in a quiet or energy saving state where the electrical device is not drawing further power from the network.

  Further advantageous refinements are disclosed in the exemplary embodiments and the dependent claims described below.

It is a figure which shows the network structure for carrying out remote electric power feeding to the apparatus by which network electric power feeding is carried out. FIG. 2 is a schematic diagram of an energy saving circuit for a network powered device. 4 is a flowchart of an energy saving method for a network powered device. FIG. 6 is a diagram illustrating a voltage profile during an initialization phase based on the “Power over Ethernet” standard.

  FIG. 2 shows an energy saving circuit 6 for use in a network configuration as already described with reference to FIG.

The energy saving circuit 6 is connected to the network configuration by two supply lines 7a and 7b. These supply lines are used to provide a supply voltage V _PSE from a supply unit PSE not shown in FIG. The device does not know the polarity of the supply voltage V _PSE . This means that the rectifier BR1 is connected between the first supply line 7a and the second supply line 7b. When supply voltage V _PSE is applied, rectifier BR1 provides a DC voltage V _{PD in} the range of 36 to 57V, in particular 44V or 48V for IEEE standards 802.3af and 802.3at. This voltage is used to charge the smoothing capacitor C1, which is arranged in parallel with the downstream converter circuit 5. The smoothing capacitor preferably has a capacitance lower than 120 nF so as not to disturb the detection of the network powered device PD.

  Between the ground connection GND of rectifier BR1 and the negative connection of smoothing capacitor C1 or converter circuit 5 so that the electrical load represented by smoothing capacitor C1 and converter circuit 5 can be isolated from supply lines 7a and 7b. A switching element 8 is provided. This switching element 8 can be used to break the electrical connection between these points. Needless to say, cutting is also possible at other points. In the present exemplary embodiment, the switching element 8 is a normally off MOSFET S1. Therefore, the converter circuit 5 is connected to the rectifier BR1 only if the control input of the MOSFET S1 has an applied switching voltage.

  In order to provide an associated switching voltage for the switching element 8, the energy saving circuit 6 further comprises a control circuit 9. In the present exemplary embodiment, the control circuit 9 is shown in two parts, in particular to combine a control signal from the secondary side with a microcontroller 9a with associated voltage regulator and circuit. And a transformer 9b. Of course, a discrete circuit can be used instead of the two-part configuration having the microcontroller 9a and the transformer 9b.

  In order to supply at least a constant operating voltage to the microcontroller 9a of the control circuit 9, an energy buffer in the form of a capacitor C2 is connected between the ground output GND of the converter circuit BR1 and the two supply lines 7a and 7b. ing. In this case, the lower connection of capacitor C2 in the present exemplary embodiment is supplied with a positive voltage component from supply line 7a or supply line 7b via diode D1 or D2. Depending on the sophistication and accessibility of the rectifier circuit BR1 in the upper load path, rectification can be performed by the rectifier BR1 rather than by the diodes D1 and D2.

  Capacitor C2 is charged by what is known as a detection pulse in the “Power over Ethernet” (PoE) standard to hold enough charge ready to power the microcontroller Dimensioned. As an example, the PoE standard has provisions for voltage pulses between 2.7 and 10 V, which are regularly provided by the supply unit PSE. Based on this standard, the minimum off time between successive pulses is at least 2 s. Thus, for example with a capacitance of 100 nF, it is possible to supply the operating voltage continuously to a particularly energy saving microprocessor with a current draw of, for example, 25 nA.

  Specific signaling in the present exemplary embodiment is described in more detail below with reference to the flowchart shown in FIG. 3 and the voltage profile shown in FIG.

  Initially, the network-powered device PD is switched off. In this state, the switching element 8 is open. This means that the converter circuit 5 does not provide any operating voltage for supplying power to the electrical equipment. In this operating state, the supply unit PSE insulates the voltage source 2 from the supply lines 7a and / or 7b according to the standard.

  However, in this operating state, what is known as a detection pulse 10 is regularly provided by the supply unit PSE. The characteristics of the detection pulse 10 are shown in FIG. Detection pulse 10 is rectified by diodes D1 and D2 and parts of rectifier BR1 and used to charge capacitor C2 (step 31).

  In this operating phase, the energy saving circuit 6 has an internal resistance higher than a predetermined limit value, for example 33 kΩ. Therefore, the monitoring circuit 3 does not recognize that the network-powered device PD is connected to the supply unit PSE, and itself enters an energy saving state until the next detection pulse 10 is emitted.

  When the secondary switch-on signal is received via the transformer 9b, the microcontroller 9a of the control circuit 9 is activated (step 32). The switch-on signal is used as a trigger pulse for the control circuit 9. As an example, it may relate to pressing a switch-on pushbutton switch located on the secondary side on a network-powered device PD.

  When such a switch-on control signal is present, the control circuit 9 activates the switching element 8 by applying an appropriate control voltage (step 33). The converter circuit 5 is thus connected to the supply lines 7 a and 7 b and to the energy saving circuit 6.

  When the next detection pulse 10 is received, the converter circuit 5 reacts according to the log record on which the protocol used is based. This means that the monitoring circuit 3 of the supply unit PSE can recognize the connection of the device PD. In particular, the increase in current flow through supply lines 7a and 7b results in a relatively large voltage drop across resistor R (step 34). As an example, a network-powered device PD has an internal resistance in the range of 15 to 33 kΩ in this operating phase, based on the PoE standard.

  In response to successful detection, the supply unit PSE then sends one or more “classification pulses” 11 to the network-powered device PD. Then, the monitoring circuit 3 of the supply unit PSE discriminates current drawing by the device PD that is network-fed. For example, to determine one of four possible power classes for the device PD.

Only after successful power class signaling, in the switch-on phase 12, the supply unit PSE activates a supply voltage V _PSE , for example between 44 and 48V. In this state, both the supply unit PSE and the network-powered device PD are fully switched on. In this operating state, in order to permanently connect the converter circuit 5 to the supply lines 7a and 7b, the control circuit 9 holds the activation signal for the switching element 8 at a predetermined value.

  When the network-powered device PD needs to be isolated from the supply lines 7a and 7b again, the secondary side of the network-powered device PD signals a suitable disconnect signal to the control circuit 9. By way of example, this may involve a disconnect signal generated by software or hardware. As soon as the second circuit part 9b of the control circuit 9 recognizes the disconnect signal (step 35), the converter circuit 5 is isolated from the supply lines 7a and 7b (step 36), so that the switching element 8 is opened. Deactivated. Devices powered by the network are disconnected.

Thereafter, the supply unit PSE recognizes the increase in internal resistance at its supply output and then deactivates the supply of the supply voltage V _PSE . Therefore, the supply unit PSE can enter an energy saving state in which only the detection pulse 10 is released at a predetermined time interval as described above. Thus, the supply unit PSE and the network-powered device PD are again in a very low power draw. As a result, the requirements of current and future standards for energy efficiency in what is known as a standby state can be observed.

  The above circuit arrangement and method are particularly suitable for supplying power to terminals that are switched on and off under user control. Such devices are particularly known as zero clients, which simply have a graphic chip for displaying a screen mask and a simple interface connection for connecting a keyboard, mouse and similar input devices. It is. In this case, the actual computing power is provided by a centrally operated server system. The use of such a minimally designed terminal unit that is also remotely powered particularly efficiently over the network allows in particular to improve the energy efficiency of medium and larger enterprise networks in particular. In this case, each user can individually switch his or her terminal on or off, as is known from a single station computer.

  The energy saving circuits and associated methods described above are equally suitable for use in various standards for remotely powered devices. In this case, the only important aspect of the circuit operation is that the voltage pulses are transmitted more or less regularly over the network line used to connect the network powered devices.

  This is not necessarily related to the detection pulse 10 based on the PoE standard. It is also conceivable to use other or additional data, signaling or supply pulses from the network protocol for charging the energy buffer C2. In particular, a relatively powerful microcontroller used as a control circuit can be provided with sufficient operating voltage if the supply unit also regularly emits classification pulses or temporarily enters the start phase. .

  For the method according to the invention, the remote power supply is performed via the wire pair itself for signaling data or via a separate wire pair of network lines as shown in FIG. It may not be important.

DESCRIPTION OF SYMBOLS 1 Network cable 2 Voltage source 3 Monitoring circuit 4 Rectifier 5 Converter circuit 6 Energy saving circuit 7 Supply line 8 Switching element 9 Control circuit 10 Detection pulse 11 Classification pulse 12 Switch-on phase
PSE supply unit
PD network powered device
S1 MOSFET
C1, C2 capacitors
BR1 Rectifier
D1, D2 diode
R resistor
Sw switching element
V _PSE supply voltage
V _PD DC voltage
V _OUT operating voltage

Claims (11)

An energy-saving circuit for the network-powered device, comprising a converter circuit (5) for generating an operating voltage for the network-powered device from a supply voltage that can be provided over the network 6) With:
At least one switching element that interrupts at least one electrical connection between the network and the converter circuit;
At least one control circuit for activating the at least one switching element based on a control signal received from the device for switching on and / or switching off;
At least one energy buffer for storing energy from voltage pulses (10, 11) provided via the network to supply operating power to the control circuit;
Energy saving circuit.   2. The energy buffer is in the form of a capacitor, and the buffer capacitance is ratioed to be sufficient to provide operating power to the control circuit for a predetermined time period. Energy saving circuit.   2. The at least one rectifier circuit (BR1, D1, D2) arranged between at least two supply lines (7a, 7b) of the network and the energy buffer of the energy saving circuit. Or the energy saving circuit of 2 description.   4. The energy saving circuit according to claim 1, wherein the at least one switching element is in the form of a semiconductor switching element, in particular a MOSFET. A supply unit for recognizing a network-fed device and supplying a supply voltage thereto;
At least one network powered device comprising an energy saving circuit according to any one of claims 1 to 4;
Having at least one network cable interconnecting the supply unit and the at least one network powered device;
Network configuration.   The converter circuit of the supply unit and the at least one network-powered device is based on a “power over Ethernet” standard, a detection pulse based on the “power over Ethernet” standard and / or 6. The network configuration according to claim 5, wherein a classification pulse is used to charge the energy buffer.   The network cable is electrically connected to at least two wires for providing the supply voltage and the wire for transmitting data from and / or to the network powered device 7. A network arrangement according to claim 5 or 6, comprising at least two further wires that are insulated. The network cable has at least four wires for providing the supply voltage and / or for transmitting data from and / or to the network powered device The network configuration according to any one of claims 5 to 7, wherein the data to be modulated is modulated as a high frequency signal on a DC voltage (V _PD ) used as a supply voltage. An energy saving method for a network powered device (PD) comprising:
The power from the voltage pulses (10, 11) provided via the network is stored in the energy buffer;
The control circuit is operated with the power stored in the energy buffer;
A first device side control signal for switching on the network powered device is recognized by the control circuit;
-A switching element is actuated by the control circuit to make an electrical connection between the network and a converter circuit of the network-powered device;
Energy saving method. The energy saving method according to claim 9, comprising:
After the electrical connection is made, the next step is:
A detection pulse is recognized by the converter circuit;
The power unit of the electrical device (PD) is recognized by a supply unit in the network;
Providing a supply voltage via the network by the supply unit;
Generating an operating voltage (V _OUT ) for operating the device (PD) by the converter circuit from the supply voltage provided via the network;
Energy saving method. 11. An energy saving method according to claim 9 or 10, comprising the following additional steps:
A second device side control signal for switching off the network powered device (PD) is recognized by the control circuit;
The switching element is actuated by the control circuit to disconnect the electrical connection between the network and the converter circuit of the electrical device (PD);
Energy saving method.

Images